A new developmental system is proposed to study molecular mechanisms related to multipotency and development in general. The advantage, of the indirectly developing annelid proposed, lies in its very simple stereotypic embryogenesis, fast development into a minute larval stage, and most importantly, maintenance of discrete undifferentiated multipotent precursor cells in charge of constructing major portions of the adult body. These cells provide a unique in vivo experimental system to identify general mechanisms related to multipotency. This project will develop several tools for future projects at the same time that investigates chromatin-remodeling processes potentially relevant to multipotency. Current gene expression studies in the PI's laboratory have identified a histone variant tightly associated with multipotent precursor cells. This histone variant is extremely conserved among animals, and therefore it is expected to perform the same function in polychaetes and vertebrates. This project aims to develop several tools that will help to functionally characterize the transcriptional developmental role of this histone variant. The first round of experiments will deplete this histone variant from individual blastomeres of the multipotent terminal growth zone. Such depletion may disrupt the developmental potential of the blastomeres in the terminal growth zone and drive unnatural differentiation of its otherwise multipotent precursors. The second round of experiments will express this variant in blastomeres undergoing differentiation with the expectation that these blastomeres will retain their developmental potential and unnaturally respond to later inductive events or ectopic transcription factor expression. A subset of experiments will test the potential of this histone variant to promote transdifferentiation, which is also a natural process associated with developmental expression of this histone variant. Understanding the molecular mechanisms that control multipotency will greatly enhance future therapeutic solutions. The first objective is to identify the effector genes that set the peculiar transcriptional state of multipotency. The ultimate goal is to manipulate these genes and reprogram in vivo differentiated cells into multipotent stem cells. Understanding the molecular mechanisms that control multipotency will greatly enhance future therapeutic solutions. The first objective is to identify the effector genes that set the peculiar transcriptional state of multipotency. The ultimate goal is to manipulate these genes and reprogram in vivo differentiated cells into multipotent stem cells. [unreadable] [unreadable] [unreadable]